Paradise does not exactly come to mind when strolling past the neat rows of unornamented concrete apartments that make up La Cité des États-Unis, or City of the United States — one of France’s first modernist social housing complexes, in Lyon’s unpretentious Eighth Arrondissement.

A few graffiti tags mark the six-story walls. Couscous and kebab restaurants are sleepy in the midafternoon lull. Groups of young men hang out on the sidewalk and flirt with women, as elderly French couples and young immigrant families go about their business.

But the 1,410-unit housing complex was considered a utopian model when it was built, largely in the 1920s and early ’30s, offering such enlightened amenities as private bathrooms, running water and garbage collection. Now, three-quarters of a century later, it is the first stop on a new tour — called Utopies Réalisées, or Achieved Utopias — of efforts by modern architecture to devise ideal places to live.